Ion Exchange Equilibrium Studies on Sulfonated Polystyrene Cross-Linked with Pure Divinylbenzenes

Abstract

Equilibrium isotherms of Na-H, K-H, Rb-H, Cs-H, and Ag-H systems for series of sulfonated polystyrene resins prepared from styrene and m- and p-DVB copolymers (2, 4, 8 mole % DVB) have been studied at 25[ddot] C. The difference between the selectivity coefficient (K_H ^M) for the 8 mole % m-DVB resin and that for the para isomer resin is relatively large and increases with the natural order of affinity of the cations up to the silver ion. The isotherms of the commercial DVB resin are also different. The variation of K_H ^M with the cationic composition (X_R) of the p-DVB resin is larger than that of the m-DVB resin as can be seen in the variation in the slope of plots. These facts are explained in terms of a variation in ion exchange sites which are related to the network structure of the copolymers. This indicates that the exchange sites are more uniformly distributed in the m-DVB resin that in the para isomer resin.